taucs_chget

Syntax

Arguments

a scilab sparse matrix (you get the upper triangle i.e. Ct is equal to C')

p

column vector storing the permutation

Description

This function may be used if you want to plot the sparse
pattern of the Cholesky factorization (or if you code something which
use the factors). Traditionally, the factorization is written :

PAP'=CC'

with P' the permutation matrix associated to the permutation p.
As we get the upper triangle Ct (= C'), in scilab syntax we
can write :

A(p,p)=Ct'*Ct

Examples

// Example #1 : a small linear test systemA=sparse([2-1000;-12-100;0-12-10;00-12-1;000-12]);Cp=taucs_chfact(A);[Ct,p]=taucs_chget(Cp);full(A(p,p)-Ct'*Ct)// this must be near the null matrixtaucs_chdel(Cp)